Does seam itself affect baking?
The normals of your mesh are facing inwards and need to be flipped. You can display your face normals, if you switch to Edit Mode, then go to your "Menu Bar - Overlay" and activate "Display face normals as lines".



Go to "Menu - Mesh - Normals - Flip Normals" to force them to face into the correct direction.



Head meshes tend to have that problem sometimes. "Recalculate Outside/Inside" doesn't fix it, because the mesh has some convex/concave areas and (in many cases) isn't closed (hole in the bottom)